Electron ray tube



May 23, 1939. Y L, sci-" F 2,159,712

' ELECTRON RAY TUBE Filed April 20. 1934 \NVENTOR LUDflWIG SCHIFF ATTORN EY S Patented May 23, 1939 UNITED STATES ELECTRON RAY TUBE Ludwig Schifi, Berlin-Lichterfelde, Germany, assignor to the firm'Fernseh A.-G., Berlin-Zehlendorf, Germany Application April 20, 1934, Serial No. 721,578

In Germany 9 Claims.

The invention relates to electron ray tubes for the purposes of television, of picture telegraphy and the like. The electron ray tubes can be employed both for transmission and also for recep- 5. tion. In the transmitter and in the receiver, the electron rays are so synchronously distributed that the pictures are scanned in a harmonious manner.

Both in the transmitter and in the receiver as great a picture surface as possible is now desired. In the transmitter it is desired in order that the picture to be transmitted may be scanned as accurately as possible.

Still more important is the size of the picture surface in the receiver. Television first attains its complete value when the picture produced can be simultaneously seen clearly by all the people present in a room or by everybody in a cinema-theatre.

With the present cathode ray tubes very serious difiiculties arise, however, in the way of increasing the picture surface. Above all the cathode ray tube has to be given an exceptional length. By this the cost of the tubes would be not only increased to a very great extent, which, especially for reception apparatus that must remain attainable by the general public, would be practically impossible, but it would also be harmful to correct picture transmission. A size of picture of about e. g. x 3 m. sufiicing for a cinema- O theatre would not indeed be practically attainable with the present cathode ray tubes, as the tubes would require a length of about 15 m. and over. It is also scarcely practically possible to 3 enlarge by projection in the optical manner a small televised picture, as it is known that in this way about 98-99% of the intensity of light of the televised picture would be lost.

Furthermore indeed by a great length of tube the exactness of picture transmission is interfered with, as the individual electrons collide with each other on their long journey and, besides, there is correspondingly often the possibility of their hitting against gas molecules, whereby a scattering of the pencils of rays of electrons will be effected. In addition the influence of the earths magnetic field and of other foreign deleterious fields is correspondingly great if the rays of electrons have a long journey.

According to the invention for the purposes of television, picture telegraphy and so forth it is possible to obtain a large picture surface with a proportionately short electron-tube, and to avoid the said disadvantages and thereby attain the novel technical advances hereinafter set forth,

August 8, 1931 so that an electron image, that is not made visible, obtained in a plane, the first picture plane, in the interior of the electron-tube, is reproduced on a larger scale in a second picture plane. This enlarged electron-image can either itself be made 6 visible or can likewise remain invisible, and be subjected to one or more further enlargements.

It is known that the rays of electrons can be assembled e. g. by electro-magnetic concentrating coils or by electro-static electrodes in an analogous manner to light rays by lenses, and that on this property of the electron rays socalled Electron-optics have been based, which have been employed for the attainment of one or more stages of enlargement of a real electronimage especially for the construction of electron microscopes. In this connection, however, it is always a question of the enlargement of still images, not for the purposes of television or of picture telegraphy, in which the object or the picture is transmitted by dots and scanned by dots.

A real still electron image, which is to be enlarged in one or more stages, is not generally present e. g. in reception apparatus for the purposes of television and picture telegraphy, but the bright or dark electron-image elements corresponding to the scanning are obtained consecutively only by dots in the plane of the real image.

For the exact purposes of television and picture telegraphy quite special technical advantages, which hitherto have not yet been known and realised, can be obtained now, by the enlargement of the electron-image arising in the scanning period.

The enlargement of the electron image within the electron-ray tube by projection from the first picture plane on to the second picture plane necessitates a much smaller length of construction of the tube than would be necessary in an ordinary tube for the direct attainment of a similarly large electron image. On the contrary by this enlargement the keeping of the first elec-. tron-image as small as desired is rendered possible, whereby the exact deflection is facilitated, the necessary deflecting tension diminished, the size and the capacity of the diffusion plates are reduced, the production costs of the tubes are diminished and the manipulation of the tube is facilitated and simplified.

In similar manner, as by the disposal of optical lenses in series the enlargement of a visible ob-- ject can be increased within wide limits, so it is possible to enlarge within very wide limits the Fig. 1 shows an electron ray tube which is ap;

plicable as a transmitter for televised pictures.

in is the vacuum tube which is widenedlike a funnel at its lower end I l. The electrons are produced by the cathode filaments l2 and urged to the anode l3 by the tension of the battery l4 disposed between the anode and the cathode. The pencil of electron rays leaving the anode I3 is now according to the invention concentrated by the collecting coil l5 not in the plane i6 closing the tube but in a plane I! lying in the inner tube, the first pictureplane. The pencil of rays is now so deflected by the pairs of electrodes l8, I9, in a manner known per se, that the focus describes a sinuous or zig-zag line in the first picture planei l. The image of these lines is now reproduced on an enlarged scale in the plane liiby means of the exactly adjustable collecting coil 20. In the plane lfithereis a system of photo cells 2| on which the. picture 22 to be transmitted is reproduced by. means of a glass lens 23 in known manner. The powerful current impulses corresponding to thedifferent brightness of the individual image points are led through the common anode 24 in known manner to the grid of an amplifying tube25 and applied, e. g., to the modulation of a highirequency transmitter. The advantage of the invention lies for an equal length of tube in a greater number. of photo cells being ableto .be obtained and. thus a finer screening of the picture to be transmitted.

Fig. 2 illustrates another construction of a transmission tube for television.

A proportionately small image of the subject 22 to be .transmittedis projected onto the photoelectric layer (cathode) 21 through the Window 26 of the tube by-the lens 23. The electrons leaving, ingreater or smaller number each according to their strengthofiillumination the individual points of the photo-electric layer 2'lwhich represent an electron image corresponding to the opticalimage, are urged-from the grid anode 28-by the. tension of the battery M. The photo-electric layer 2? here represents the first picture plane.-The electronimage of the first picture plane isin contrast'to-the arrangement illustrated in Fig. lsimu1taneously reproduced in the second picture-plane I6 as a whole by means of the collecting coil 20 and displaced in a zigzag manner as a whole by deflection by means of the pair of deflecting plates l8, l9 and scanned by the peak (or end) of the fixed electrode 29. The current fluctuations are directed in known manner to the amplifying tube 25.

The intense enlargement by the collecting coil 20 advanced very near to the cathode 21 permits of keeping very small the image surface 21 and therefore the cross section of the pencil of rays leaving it which renders possible small proportions and small capacity of the deflecting plates. In spite of the great enlargement the transmission tube is only a proportionally short length of construction.

Fig. 3 illustrates a reception-tube 30 which is widened funnel-like at its lower part 3|. The

electrons are produced through the incandescent cathode l2 by means of the battery l4 and the anode I3. The intensity of the pencil of rays of electrons in the opening of the screen 32 is altered in the rhythm of the current fluctuation arriving from the transmitter by the control electrode 33. The orifice of the screen 32 is reproduced in the first picture plane I! lying in the interior of the tube in accordance with the invention by the collecting coil l5. An electron picture is produced in the plane I! by the lateral regulation of this image point by means of the deflecting plates I8, i3 and by the simultaneous regulation of intensity by means of the electrode 33. This picture is reproduced in the picture plane E6 on an intensely enlarged scale by collecting coil 20 advanced adjacent to the plane I! and in known manner is made visible by a fluorescent layer disposed in this plane. Thus a very large image is produced in the plane l6 with a short length of construction. of the tube. For the production. of, especially large pictures-it is forthwith. possible to employ, notonly one intermediate image but a plurality of intermediate.

images. i

In accordancewith the invention also, instead of the magnetic collecting apparatus, electric collecting apparatus or a combination of bothcan be employedfor the enlargement of electron images.

I claim:

1. An electron ray tube for the purposesof television, picture telegraphyand the like comprising in combination an evacuated container, means for producing in said container in spaced planes a plurality'of electron images one of which is an enlargement of another, said means comprising a cathode filament, an anode, an electric current supply means connected between said cathode filament and said anode, a first collecting coil between said anode and the first image plane of the tube, pairs olf deflecting electrodes between said coil and the first image plane of said tube, and an adjustable second collecting coil between said first image plane and the second image plane of the tube.

2. An electron ray tube for the purposes of television picture telegraphy and the like comprising in combination an evacuated container, means for producing in said container in spaced planes-a plurality of electron images one of which is an enlargement of another, said means comprising a cathode filament, ananode, an electric current supply meanselectrically connected between said cathode and said anode, a first collecting coil between said anode and the-first image plane of the tube, pairs of deflecting electrodes between said coil and said first image plane ofthe tube, a second adjustable collecting coil between said first image plane and a photo-electric device in the second image plane of the tube, an anode for saidphoto-electric device, an amplifier electrically connected to said photo-electric device, and an optical device for reproducing on said photo-electric device the picture to be transmitted.

3. An electron ray tube for the purposes of television, picture telegraphy and the like comprising in combination an evacuated container, means for producing in said container in spaced picture planes a plurality of electron images one of which is 7 an enlargement of another, said means comprising a cathode photo-electric device in the first picture plane of the tube, an

anode, an electric current supply means electrically connected between said cathode and said anode, pairs of deflecting electrodes between said anode and the second picture plane of the tube, a collecting coil between said anode and said defleeting electrodes, a fixed electrode in said second picture plane, an amplifier electrically connected to said fixed electrode, and an optical device for reproducing on said photo-electric device the picture to be transmitted.

4. An electron ray tube for the purposes of television, picture telegraphy and the like comprising in combination an evacuated container, means for producing in said container in spaced picture planes a plurality of electron images one of which is an enlargement of another, said means comprising a cathode filament, an anode, an electric current supply means connected between said cathode and said anode, a first collecting coil between said anode and the first picture plane of the tube, means for adjusting the intensity of the electron rays in accordance with the rhythm of the current fluctuations arriving from the transmitter, pairs of deflecting electrodes between said coil and the first picture plane of the tube, and an adjustable second collecting coil between said first picture plane and the second picture plane of the tube.

5. An electron ray tube for the purposes of television, picture telegraphy and the like comprising in combination an evacuated container, means for producing in said container in spaced picture planes a plurality of electron images one of which is an enlargement of another, said means comprising a cathode photo-electric device in the first picture plane of said tube, a grid anode, an electric current supply means electrically connected between said cathode device and said grid anode, pairs of deflecting electrodes between said anode and the second picture plane of the tube, a collecting coil between said anode and said deflecting electrodes, a fixed electrode in said second picture plane, an amplifier electrically connected to said fixed electrode, a lateral window in said container, and an optical device for reproducing through said window on said photo-electric device the picture to be transmitted.

6. An electron ray tube for the purposes of television, picture telegraphy and the like comprising in combination an evacuated container,

means for producing in said container in spaced picture planes a plurality of electron images one of which is an enlargement of another, said means comprising a cathode filament, an anode, an electric current supply means electrically connected between said cathode and said anode, a first collecting coil between said anode and the first picture plane of the tube, a screen between said anode and said first collecting coil, regulating means between said anode and said screen, pairs of deflecting electrodes between said coil and the first picture plane of the tube, and an adjustable second collecting coil between said first picture plane and the second picture plane of the tube.

7. An electron ray tube for the purposes of television, picture telegraphy and the like comprising in combination an evacuated container having a widening like a funnel at one end, means for producing in said container in spaced planes a plurality of electron images one of which is an enlargement of another, said means comprising a cathode filament, an anode, an electric current supply means electrically connected between said cathode and said anode, a first collecting coil between said anode and the first image plane of the tube, pairs of deflecting electrodes between said coil and said first image plane, a second, adjustable collecting coil between said first image plane and a photocell device adjacent the outer end of the funnel part of the container in the second image plane of the tube, an anode for said photocell device, an amplifier electrically connected to said photocell device, and a glass lens device for reproducing on said photocell device the picture to be transmitted.

8. An electron ray tube for the purposes of television, picture telegraphy and the like comprising in combination an evacuated container, means for producing in said container in spaced picture planes a plurality of electron images one of which is an enlargement of another, said means comprising a cathode photo-electric device in the first picture plane of the tube, an anode, an electric current supply means electrically connected between said cathode and said anode, deflecting means located between said anode and the second picture plane of the tube, an electric lens between said anode and said deflecting means, a fixed electrode in said second picture plane, an amplifier electrically connected to said fixed electrode, and an optical device for reproducing on said photo-electric device the picture to be transmitted.

9. Apparatus for television, picture telegraphy and the like comprising in combination, an evacuated container, means for establishing an electron beam within said container, an electric lens for focusing said beam in a plane in said container,. scanning means located between the source of said beam and said plane for sweeping said beam over an extended area in said plane, and a second electric lens arranged to act upon the beam proceeding from said plane to focus said scanned beam on an enlarged area in a second plane within said container.

LUDW'IG SCI-EFF. 

